Effect of stress layer on thermal properties of SnSe2 few layers

Layered SnSe2 have much attention due to their potential novel applications in electronic devices areas, such as photo-transistors, solar cells and memory devices. We investigate the thermal properties of few layer SnSe2 with capping of Al2O3 layer using the temperature and power-dependent Raman spectroscopy. The first order temperature coefficient of A(1)(g) modes of SnSe2 layers on a SiO2/Si substrate was found to be -0.01757 cm(-1)/K, which is much higher than the corresponding value -0.01270 cm(-1)/K of SnSe2 with Al2O3 layer. The difference in temperature coefficients is attributed to compressive stress introduced by the Al2O3 stress layer. Meanwhile, the Al2O3 layer significantly increases the thermal conductivity to 3.102 W/mK, which is larger than that of the SnSe2 films without Al2O3 (similar to 2.378 W/mK). The first principle calculation using CASTP demonstrated that this improvement of thermal conductivity is attributed to the compressive strain. This work suggests an effective way to improve the performances of SnSe2 based devices, and also need to understand the vibrational properties and electron-phonon interactions at the interface of Al2O3 and SnSe2 layers. (C) 2018 Elsevier B.V. All rights reserved.